"Tonight, it's much more than just watching a football match, it's a challenge to Daesh," said Qais, using an Arabic acronym for the Islamic State (IS) group.

"Until recently, I'm sure Ronaldo had never heard of Balad. Now he has worn the black arm band for our martyrs," the 29-year-old said.

"I hope he scores at least one tonight," he added, shortly before his idol and his teammates jogged onto the pitch to face Madrid rivals Atletico in the Champions League final.

IS, a jihadist organisation that has sewn death destruction in Iraq for two years, claimed responsibility for the attack, although the exact circumstances of the raid and its aftermath remain unclear.

The carnage sparked an outpouring of sympathy from the football world, including from Real Madrid, whose players wore the black arm band for their final Spanish league game the following day.

"The reaction of the club gave us great joy," said Qassem Issa, the 39-year-old businessman from Balad who founded the supporters club seven years ago.

"Of course, before the attack, we were planning to watch the final here. There was some hesitation but eventually we insisted to spend the evening here, as a show of strength," he said.

Iraqi forces are currently fighting to retake the IS bastion of Fallujah, one of their toughest battles yet.

- Muted joy -

In the Al-Furat cafe's large garden, festooned with multi-coloured light bulbs and posters of the victims, officials, residents and poets took turns to honour the victims.

Dozens of police men armed with assault rifles were deployed around the cafe to protect the venue and frisk the young men flocking to watch the final.

Survivors of the May 13 massacre stayed home but many Balad youths who lost brothers and friends wept during the hour-long ceremony.

"I was the first one in the cafe after some people came running out shouting that there was an attack going on," Firas Hatef recalled.

"The first thing I saw when burst in with my pistol was my 17-year-old son Sajad, lying on the floor face down, dead," he said.

"He had a bullet wound in the head and another in the neck," he said. "I also lost a brother in the attack. All of this because we like watching our team?"

IS and other jihadist groups consider football a product of the Western society they despise and sport venues have repeatedly been targeted.

A suicide bomber blew himself up on March 26 during a trophy ceremony after a local football tournament south of Baghdad, killing more than 30 people, many of them teenagers and children.

When Ronaldo finally slotted in the winning penalty kick late Saturday, the joy in the Al-Furat cafe was muted as fans broke down in tears remembering their fallen friends and relatives.

Extra time pushed the game past the midnight curfew that is slapped on Balad every night for security reasons and the dyed-in-the-wool supporters who had risked staying on hurried back home as soon as the match ended.